1. Field of the Invention
The present invention relates to a method of generating raster data on the basis of respective contour vectors of graphic figures. The raster data is useful to produce a multitone image containing the graphic figures through a raster scan of an image plane for each scanning line, where the term "graphic figures" expresses character fonts, geometric figures and other graphic information that may be represented on a plane.
2. Description of the Background Art
In the field of commercial printing and the like, techniques for automatically reproducing an image containing a plurality of graphic figures through a raster scan have been developed. In one of the techniques, raster data for generating run-length codes are obtained by finding intercrossing points of scanning lines and contours of the graphic figures and then sorting and merging the intercrossing points according to respective main scanning condinates thereof.
However, the prior art can be applied only to binary images, and no techniques have been proposed for systematically generating raster data in order to reproduce a multitone image. Therefore, when it is required to reproduce a multitone image through a raster scan, an original image is produced through manual operation, and image data of a photosensitive material for the raster scan is generated by reading the original image with a photoelectric image reader. Such a manual operation is laborious, and requires much time to obtain desired raster data.